With the development of technology, synthetic fibers have also been improved to have physical properties comparable to those of natural fibers, and thus synthetic fibers having various functionalities have been used. In particular, polyesters represented by polyethylene terephthalate have many excellent properties, and thus have been widely used not only for textile applications but also for industrial applications.
Recently, in the polyester textile industry, high value-added differentiated materials have been actively developed. In an effort to overcome the disadvantages of polyesters and develop new advantages, many studies focused on modifying the components of polyester polymers with other components or adding special additives to polyester polymers have been conducted.
As an example, European Patent No. 302141 discloses a polyester fiber having thermal storage and insulation properties, which contains zirconium carbide particles. However, zirconium carbide particles have a disadvantage in that they cannot provide fabric products having various colors because they have a gray or black color when being incorporated into blended yarns.
Meanwhile, Japanese Unexamined Patent Application Publication No. Hei 3-69675 discloses a technology for producing a staple fiber, which includes mixing a fiber-forming polymer with an oxide ceramic fine powder such as an alumina or zirconium oxide ceramic fine powder to prepare a master chip, mixing the master chip with a general polyester chip, and spinning the mixture. The polyester fiber that is produced by this method has good whiteness, but has a problem in that the production of filaments is difficult because the dispersibility of a large amount of ceramic particles is poor.
Korean Patent No. 926588 discloses a method for producing spun yarns, which includes uniformly mixing tungsten oxide particles having a particle diameter of 1-800 nm and a hexagonal crystalline structure with a polyester resin to prepare a master batch, melt-spinning the master batch, drawing the melt-spun filaments to produce multifilament yarns, and cutting the multifilament yarns into staple yarns. However, tungsten oxide particles aggregate into large particles during the production of the master batch and the production of the yarns, and thus cause fatal problems in that the spinnability of the master batch becomes poor and appearance defects such as fluffs or loops occur. Accordingly, the yarns containing the tungsten oxide particles are actually impossible to use as long fibers, and should be used only as spun staple fibers.